    #web_bg{
        position:fixed;
        top: 0;
        left: 0;
        width:100%;
        height:100%;
        min-width: 1000px;
        z-index:-10;
        zoom: 1;
        background-color: #fff;
        background-repeat: no-repeat;
        background-size: cover;
        -webkit-background-size: cover;
        -o-background-size: cover;
        background-position: center 0;
    }

    body {
        padding: 0;
        margin: 0;
    }
    #main { 
        position: absolute;
        width: 25%; height: 70%;
        left: 50%;
        top: 50%;
        margin-left: -12.5%;
        margin-top: -17.5%;
        border-radius:5%;
        transition: 0.75s;
        opacity: 1;

    }

    #card1 {
        width: 100%; 
        height: 100%;
        background-color: #1E90FF;
        border-radius:5%;
        background:url(../images/main.jpeg);
        background-size:100% 100%;
        background-repeat:no-repeat;
        backface-visibility: hidden;
    }

    #card2 {
        position: absolute;
        width: 100%; height: 100%;
        border-radius:5%;
        background-color: rgb(255, 255, 255);
        background:url(../images/login.jpg);
        background-size:100% 100%;
        background-repeat:no-repeat;
        backface-visibility: hidden;
    }
    #card3 {
        position: absolute;
        width: 100%; height: 100%;
        border-radius:5%;
        background-color: rgb(255, 255, 255);
        background:url(../images/register.jpg);
        background-size:100% 100%;
        background-repeat:no-repeat;
        backface-visibility: hidden;
    }
    #c1login{
        position: absolute;
        width: 40%; height: 10%;
        left: 5%;
        bottom: 7.5%;
    }
    #c1login > button {
        width:100%;
        height: 100%;
        text-align: center;
        border-style :none; 
        background: rgba(30, 143, 255, 0.5);
        font-family: Microsoft YaHei; 
        color: black;
        font-size: 25px; 
        border-radius:15px;
        cursor:pointer;
    }
    #c1login > button:hover {
        background: #5599FF;
    }
    #c1register{
        position: absolute;
        width: 40%; height: 10%;
        right: 5%;
        bottom: 7.5%;
    }
    #c1register > button {
        width:100%;
        height: 100%;
        text-align: center;
        border-style :none; 
        background: rgba(30, 143, 255, 0.5);
        font-family: Microsoft YaHei; 
        color: black;
        font-size: 25px; 
        border-radius:15px;
        background-size: cover;
        cursor:pointer;
    }
    #c1register > button:hover {
        background: #5599FF;
    }
    #c1mp{
        position: absolute;
        bottom: 0;
        left: 40%;
        width: 20%; height: 7.5%;
        text-align:center;
        font-family: Microsoft YaHei; 
    }
    #c1mp> button {
        width:80%;
        height: 50%;
        bottom: 20%;
        left: 10%;
        position: absolute;
        text-align: center;
        border-style :none; 
        background: rgba(30, 143, 255, 0.5);
        font-family: Microsoft YaHei; 
        color: black;
        font-size: 80%; 
        border-radius:5px;
        background-size: cover;
        cursor:pointer;
    }
    #c1mp > button:hover {
        background: #5599FF;
    }
    #c21{
        position: absolute;
        top: 35%;
        width: 100%; height: 10%;
        text-align:center;
        font-family: Microsoft YaHei; 
    }
    #c22{
        position: absolute;
        top:50%;
        width: 100%; height: 33%;
        text-align:center;
        font-family: Microsoft YaHei; 
    }
    #c23{
        position: absolute;
        top :68%;
        width: 100%; height: 33%;
        text-align:center;
        font-family: Microsoft YaHei; 
    }
    #c23> button {
        width:25%;
        height: 25%;
        position: absolute;
        left: 37.5%;
        bottom: 40%;
        text-align: center;
        border-style :none; 
        background: rgba(30, 143, 255, 0.5);
        font-family: Microsoft YaHei; 
        color: black;
        font-size: 25px; 
        border-radius:15px;
        background-size: cover;
        cursor:pointer;
    }
    #c23 > button:hover {
        background: #5599FF;
    }
    #c24{
        position: absolute;
        top :68%;
        right: 0%;
        width: 50%; height: 33%;
        text-align:center;
        font-family: Microsoft YaHei; 
    }
    #c24> button {
        width:32%;
        height: 40%;
        position: absolute;
        right: 20%;
        bottom: 40%;
        text-align: center;
        border-style :none; 
        background: rgba(30, 143, 255, 0.5);
        font-family: Microsoft YaHei; 
        color: black;
        font-size: 10px; 
        border-radius:5px;
        background-size: cover;
        cursor:pointer;
    }
    #c24 > button:hover {
        background: #5599FF;
    }
    #c31{
        position: absolute;
        top: 40%;
        width: 100%; height: 10%;
        text-align:center;
        font-family: Microsoft YaHei; 
    }
    #c32{
        position: absolute;
        top:47.5%;
        width: 100%; height: 15%;
        text-align:center;
        font-family: Microsoft YaHei; 
    }
    #c33{
        position: absolute;
        top:55%;
        width: 100%; height: 15%;
        text-align:center;
        font-family: Microsoft YaHei; 
    }
    #c34{
        position: absolute;
        top :68%;
        width: 100%; height: 33%;
        text-align:center;
        font-family: Microsoft YaHei; 
    }
    #c34> button {
        width:50%;
        height: 25%;
        position: absolute;
        left: 25%;
        bottom: 40%;
        text-align: center;
        border-style :none; 
        background: rgba(30, 143, 255, 0.5);
        font-family: Microsoft YaHei; 
        color: black;
        font-size: 25px; 
        border-radius:15px;
        background-size: cover;
        cursor:pointer;
    }
    #c34 > button:hover {
        background: #5599FF;
    }
    #c35{
        position: absolute;
        top :68%;
        right: 0%;
        width: 50%; height: 33%;
        text-align:center;
        font-family: Microsoft YaHei; 
    }
    #c35> button {
        width:32%;
        height: 40%;
        position: absolute;
        right: 20%;
        bottom: 40%;
        text-align: center;
        border-style :none; 
        background: rgba(30, 143, 255, 0.5);
        font-family: Microsoft YaHei; 
        color: black;
        font-size: 10px; 
        border-radius:5px;
        background-size: cover;
        cursor:pointer;
    }
    #c35 > button:hover {
        background: #5599FF;
    }
    #c23mp{
        position: absolute;
        top :68%;
        width: 50%; height: 33%;
        text-align:center;
        font-family: Microsoft YaHei; 
    }
    #c23mp> button {
        width:32%;
        height: 40%;
        position: absolute;
        left: 20%;
        bottom: 40%;
        text-align: center;
        border-style :none; 
        background: rgba(30, 143, 255, 0.5);
        font-family: Microsoft YaHei; 
        color: black;
        font-size: 10px; 
        border-radius:5px;
        background-size: cover;
        cursor:pointer;
    }
    #c23mp > button:hover {
        background: #5599FF;
    }